Centrifugal separator



Oct. 11, 1960 A. NYROP CENTRIFUGAL sEPARAToR Filed July l1, 1958 i mllll INVENTOR l... ipfla BY /v 2%" f2? ATTORNEY United States Patent 2,955,754 CENTRIFUGAL SEPARATOR Aage Nyrop, 18 Hans Jeusensvej, Hellerup, Denmark Filed July 11, 1958, Ser. No. 748,014 8 Claims. (Cl. 233-20) The present invention relates to improvements in centnfugal separators to separate sludge fromv liquids, and the separator is of the type having a centrifugal bowl provided with a rotatable spindle and separating chambers and comprising two parts displaceable in the axial direction relative to each other, of which parts one constitutes a closing and opening member which through the intermediary of an actuating liquid conducted through the centrifugal bowl and influenced by the centrifugal force can be displaced for the closing and opening of one or several peripheral sludge discharge openings for intermittent discharge of suspended sludge-collected within the bowl.

The term sludge as used herein is to be considered as designating not only impurities in liquids, but any material including a large proportion of solids of higher specic gravity than the liquids in which they are suspended.

In sludge separators of this type it is known to provide the separator with means, such as valves through which the actuating liquid can quickly be discharged from the centrifugal bowl in order thereby to obtain a so quick opening of the sludge discharge openings that the separated sludge or the separated solid material can be instantaneously discharged from the centrifugal bowl. By such an instantaneous discharge of the sludge or the solid material, which may e.g. be sticky, the less concentrated sludge Will carry the more concentrated sludge deposited on or sticking to the bowl wall, along out through the sludge discharge openings so that there will not be any one-sided deposit of sludge on the bowl wall which may cause undesired shakings of the centrifugal bowl. If on the other hand it is only a question of separating such matters as contain nothing but plastic sludge, e. g. organotherapeutic matters, such -as Heparin or similarv plastic substances, fruit pulp and `substances corresponding thereto, which can only be concentrated to a minor degree and frequently. do not give any rm deposit on the bowl wall, it will be advantageous, under continuous feeding of separating material to the centrifugal bowl, intermittently and partially to be able to discharge the most concentrated sludge lying nearest the periphery wall of the bowl without allowing the less concentrated sludge or cleaned liquid lying nearer the axis of rotation to escape, seeing that only the most concentrated -sludge is allowed to be discharged from the centrifugal bowl. In such a discharge of sludge from the centrifugal bowl it is not possible to use a complete opening of the sludge dis- 'charge openings which is normally established by evacuating the actuating liquid from the centrifugal bowl through an actuating valve thus obtaining, on account of the great hydrostatic pressure produced by the centrifugal force in the separating bowl as well as in chambers containing the actuating liquid, an instantaneous and complete opening of the sludge discharge openings. The said hydrostatic pressure may in a centrifugal separator of the type referred to be 50 atm. or more, which pressures are released in the course of a time interval which is less than 2,955,754 Patented Oct. l1, 19,60

a second, and so the controlling or regulating means for the regulation of the feeding of the actua-ting liquid must be exceedingly sensitive.

An important feature of the invention consists of the 'arrangement of the separator 4in such a manner that at predetermined time intervals during fthe oper-ation, the most concentrated sludge present nearest the inner circumference Wall of the centrifugal separator is discharged during the separation, while the remaining part of the sludge-containing mixture is retained for a continued lseparation and concentration of the sludge.

Another feature of the present invention is to arrange the separator in such a manner that it is possible at predetermined time intervals to obtain a controlled parti-al opening of the sludge discharge openings of the centrifugal bowl and at longer time intervals a complete opening of the sludge discharge openings of the centrifugal bowl.

Still another feature of the invention is to arrange the centrifugal separator in such a manner that it is possible to obtain such a relation between the quanti-ty of the actuating liquid continuously oozing out from the centrifugal bowl for the actuation of the closing member for the sludge discharge openings of the centrifugal bowl and the amount of the actuating liquid which is fed to the centrifugal bowl that the pressure of the lactu-ating liquid will cause said closing member 15 to be balanced during an intermittent partial opening of the sludge discharge openings.

Still another feature of the invention is to arrange the centrifugal separator in such a manner that the length of the time intervals between the sludge discharges are determined automatically by means of a timer, while the length of the time intervals during which the sludge discharges take place is determined by means of 4the energy contained in the `sludge being discharged, either through current impulses in the driving electric motor of the centrifugal separator or through the influence of the sludge on mechanical means.

Further features of the invention will be apparent from the following specification in connection with the accompanying drawing.

- The invention vas illustrated in the drawing shows` a manner of construction of the centrifugal separator according to the invention, in which Fig. 1 shows 'a partial section through the centrifugal bowl along its `axis of rot-ation and regulating members of fthe centrifugal separator,

Figs. 2, 3 and 4 details on a somewhat larger scale and in section :along the longitudinal axis, and

Fig. 5 another manner of construction -of the regulating members.

The centrifugal separator has a centrifugal bowl comprising yan upper part 1 and a lower part 2, 2a, which are held together by means of a threaded ring 3, the parts 2, 2a being arranged on a rotatable spindle 4. lThe separation material is fed through an inlet pipe 5 to the middle tube Sa of the centrifugal bowl and from there through channels 6 to the separating chamber 7. The separating chamber is provided with a suitable stack of discs 8 and accelerating wings 9. Furthermore the centrifugal bowl has sludge discharge openings 10 for a lighter liquid component and discharge openings 11 for a heavier liquid Acomponent and peripheral discharge openings 12 for the separated sludge or solid material. From the said discharge openings 12 the separated sludge or solid material is impelled into a stationary chamber 13 arranged around the centrifugal bowl through an annular slot 14 arranged in the wall of the said chamber. The discharge openings 12 may be closed and opened by means of an annular piston 1S which is axially displaceable in an incision in the bowl part 2, 2a, and can be moved towards and away from a bowl part 1. VThe piston 15 is kept against the gasket 16 bymeans of an actuating liquid inuenced by the centrifugal force. The closing liquid isintroduced into -a-chamber17 constructed .in the bowl part 2,'2a,beneath the piston 15,. The Tclosing liquid is under pressure conducted through'a tube `178 Yto .an .annular channel 19 formed in the bowl part 2, .2a and is from Ithere, under the inliuence of Ythe vcentrifugal force, im pelledV through a channelV 20 to the chamber.17. Normally through theintermediary of the intermittent opening of the sludge discharge openings 12, Ythe actuating liquid will beY conducted to the outer surroundings or exter-ior of the centrifugal bowl through .a discharge arrangegasket 16 arranged in the within 'a time interval ofl a few minutes, and a timer B2b, which can be set to operatewithin a time interval of a few seconds, thus the timer may be adjusted very exactly according to the desired times for the sludge discharges. The timer'receives its current from a couple of currentcarrying Wires 33 and 34, and it is provided with a contactor 35 which through suitable-connections can close a circuit through an electro Vmagnet 36. This magnet is ment that includes an actuating valve21 mounted in the bowl wall and counter balancedby means of apiston 22 arrangedin a chamber.23.formed .inthe bowl Ypart2, 2a andconnected to the valvecone of .theV valve- 21'by means of a rod 24 passing through an-incision25-in `the bowl part 2, 2a. Y Y Y Y When treating certain sludge containing materials, the' sludge separated in the separating chamber 7 `is'intermittently discharged through the discharge openings 12,V the supply `ot' the material through the pipeS and the supply of` actuating liquid through the tube 18 beingY stopped, and there is thereafter introduced under pressure lan actuating liquid through a tube 26 to an annularchannel 27 formed in the bowl part 2, 2a Vand `from there it is under the inuence of the centrifugal force flung through'a channel -28 to an incision 23 behind the piston l22 which is thereby caused to be moved outwardly openingthe valve 21. In this manner the Vactuating vliquid is discharged from the chamber17, and sothe hydrostatic pres- -sure in the separating chamber '7 and in a; chamber 29 above tan annular ange30 on the lpiston 15 quickly moves the piston downwards opening the sludge discharge openings 12. By such a swift and completeopening of the openings 12 all the sludge and the separating material capable of attractinglan-'armature 37 iona regulating valve 38 which is inserted in the supply pipe 1,8, andwhich in accordance with vits setting Vcau regulate the v'supply of actuating liquid to the chamber-'17; AWhen the timer 32 breaks the circuitY through the magnet 36, the magnet will release the armature 37, and thevlve 38 will now adjust itself in the manner that the pressure Von the piston 15 is reduced so much that the sludge discharge openings 12 are opened partially. When the sludge oozes out into the openings 12 andj consequently gets ata bigger distance from the axis of rotation of the centrifugal bowl, an increased energy is'required for keeping vthe bowl at Vits normal speed, or the bowl A.will be braked Ain such a manner that its speed will be reduced.` Included in the circuit of the magnet 36 is ya contactor 39 Which-through wires 40 receives current from the electric motor that drives the bowl. As above Vmentioned Ywhen sludge is flung outWard-lyfrom .the bowl through vthe openings 12, the sludge will be discharged on an increased radius, which means. that themotor will be braked; a little, that is, its

are .discharged from the separating chamber. .'When the supply of Vactuating liquid for the chamber23ris stopped, the actuating liquid present in this chamber is ,ejected through the piston 22 and on through the .opening 31 in the wall of the bowl part 2, 2a. When thereafter actuating or closing liquid is conducted to 'the chamber .17 the piston I5 is displaced towards the gasket `16 and closes the openings 12, whereafter material to be separated may Vagain be fed to the separating chamber7. g

In the treatment of sludge-containingseparating material including plastic sludge 'which can only be. concentrated to a minor degree, it is advantageous toY ,be able to discharge intermittently only the most concentrated sludge present in the separating chamber adjacent its periphery without stopping vthe supply of the separating material to theseparating chamber. For hSpllrpOse is ,required a slow and :only partial opening of the sludge discharge openings 12. To achieve this obiect `'the cenvtrifugal separator has a constantly open voozingopening 'for the actuating liquid, which operiinghas allow area notso great that itis impossible during acontinuous supply of actuating liquid, to maintin'the necessary hydro-V static 4pressure in the chamber i17 againsttheepiston 15 Ito keep Vthe sludge dischargeoper'iingsg12closed, but -through ak suitable regulationofithegsupply*of the actu- :ating liquid the hydrostaticgpressure reducedfso much that rthe sludgeV discharge openings '12 "are opencdslowly fand partially. Such regulation ofthe Vsupply'hofrzthe actufating liquid must be made attimejintervals adjusted ac- :cording tothe quantity of sludge desireddischarged at V:each opening of theopenin'gsflZ. 1t is preferable that :the 'regulation of the 'actuatingliquid is" performed 'automaticallycwithin the said`timev intervals, zthe'flatter Vbeing .determined accordingto the'nature and quaritityof the 'S`sludge`to be dischargedlf For ithis vpu/rposeiisfar-ranged aV rate of revolution `is-somewhat decreased. To 'enable the motor, after the sludge discharge, to again reach its normal rate of revolutions, it consumes fora moment an increased strength of current;.and fitV is this current impulse that is used to influence the. contactor 39. When this contactor is thus operated to close the magnetrcircuit and attract the armature 37, the valve 38 will again-be adjusted to conduct the-normal amount yof .actuating liquid to the chamber 17, whereby the pressuref on the piston 15 is increased so that the latter ,willagain close the sludge discharge yopenings 12. Instead Yof using reoccurringY-electric Vimpulses fromthe driving motor Vfor Vthe closing of the circuit through the Vmagnet 36, 'it isfpossible to use the energy in the sludge being discharged; For this kpur-- pose'it is possible, as shown in Fig. 5, to arrange .in-the y"timer 32 which 'is adapted -vvithinxthe saidtime intervals wall of the annular chamber `13 opposite the'l discharge openings 12 amembrane, or movable member -41in .connection with a contactor 42 which -isinsertedin the circuit of the magnet 36, and which closes the Vsaid circuitwhen the sludge, which is being discharged,-hits themember 41.

In the described example is used aV valve3 8 which closes by currentless solenoid coil. `Ifa corresponding valve is used'closing'by current-carrying coi1,.the .function of the contactors will be reversed, and the principle fof the inventionJthus remains unchanged. i Y Y A The oozing opening .for the oozingrout of theiactuating 'liquidmay by wayof example beperformed as illustrated in Figs.,2, 3 Vor 2l. An'oozing channel49is carried kthrough the cone of the valve 21 as in Fig. 4;'.orfthefrod 24,

connectingy the valve cone of the'va'lvej21- withthe piston 22, 'has la centralbore 43 whichvpasses `freely through the valve 21, and whichbyrmeans of an Aoozing `channel 44 is connectedV with .thevcharnber 17 .as .i'nYFigs Land 2. The oozing channel 44,isv situated at such a distance from the axis of rotation that the pressure Afromtheactuating liquid against'theapiston 15..can.only be'decreasedlto such a degree, .in relation .to the `opposed pressure, Athat `the pressure will balancethe `piston L15 `ina positiongforpartial opening Yof Ythevsludge discharge openings .12.- Y

To limit the amountvfof the actuating liquid which is Vsubjected to a comparatively ,great` pressure, theoozing channel has -a comparatively small 'cross sectionalearea,

vand to safeguard against the'possibility ofcollection in the Ychannel-of solid particleswhich may `bepresentin actuating liquid, thefoozing channelfmayby wayvof Iexample beYconstructedjnssuchafmannenthat the chan- .nel has aldecline towardsthe axisnof rotation, .thatis Yto say, the channel extends at an angle to a radial iine radiating from the axis of rotation of the bowl. Furthermore the voutlet end of the opening lies nearer the axis of rotation than is the case with its inlet opening and hence by a quick and complete discharge lfrom the chamber 17 through the valve 21 the actuating liquid will carry such solid particles away. Instead of arranging the oozing channel 44 in the valve rod 24, it can fbe yarranged in the lower part 2 of the bowl itself as shown in Fig. 3 where the xoozing channel is designated by 48. Furthermore the cross sectional area of the oozing channel may be varied for oozing out of predetermined amounts of actuating liquid per time unit by the use of interchangeable parts or elements such as 45 in Fig. 3, removably insertable in the channel, the oozing channels `or passages of which elements having different predetermined cross `sectional areas. In such a construction of the oozing channel the outlet openings of `the said parts open into a liquid reservoir 46 which has a greater cross sectional area than the cross sectional area of the oozing channels, and thus during the discharge of the sludge there will always be so much liquid 47 in the reservoir that the liquid covers the openings of the oozing channel and thus prevents solid particles from depositing in the oozing channel. In case of complete discharge of sludge and separating material from the separating chamber-the liquid 47 will be carried along by the actuating liquid discharged from the chamber 17.

I declare that what I claim is:

l. In a centrifugal separator, the combination of a centrifugal bowl mounted for rotation on a vertical axis to effect continuous discharge of liquid eiluents and provided with peripheral sludge discharge openings for suspended solid material collected within the bowl, a sealing piston for controlling the sludge discharge through said openings and mounted for axial reciprocation within the bowl, said piston being actuated to intermittent displacement partly by pressure of the treated liquid and partly by means of an actuating liquid inuenced by centrifugal force, conducting means to conduct the actuating liquid to to annular grooves in lthe bottom of the bowl and conducting means -to conduct the actuating liquid from one of the said annular grooves to a space below said piston, said space being connected with a discharge arrangement for the actuating liquid, this discharge arrangement comprising a valve means and hydrostatic means for displacement of said valve means to an open position to permit the discharge of the actuating liquid and the simultaneously resulting movement of said piston to its complete open position for sludge discharge, means to permit the actuating liquid constantly to ooze out from the said space, automatic means controlled by the energy contained in the sludge for regulating the flow rate of actuating liquid conducted to the said annular groove in relation to the rate of actuating liquid oozing out from the said space to the effect of displacing said piston to a position for `a partial opening of the sludge discharge openings in the bowl and simultaneous partial sludge discharge, said Iautomatic means holding the piston balanced in its partially open position without stopping the supply to the bowl of the material to be separated, Iand timer means associated with said automatic means for controlling the length of the partial openings and the intervals between such.

2. In the structure of a centrifugal separator as claimed in claim l in which said valve means includes a valve and said means to permit the actuating liquid constantly to ooze out from said space is a channel formed in said valve.

3. In the structure of a centrifugal separator as claimed in claim 1 in which said means to permit the actuating liquid constantly to ooze out from said space is a channel formed in the bottom of the bowl and in communication with said space below the piston, said channel extending at an angle to a radial line radiating from the axis of rotation, and a replaceable element in said channel with an oozing opening of predetermined cross sectional area.

4. In a centrifugal separator, the combination of a centrifugal bowl mounted for rotation on a vertical axis to eect continuous discharge of liquid effluents and pro.

vided with peripheral sludge discharge openings for suspended solid material collected within the bowl, an annular sealing piston for controlling the sludge discharge through said openings and mounted for axial reciprocation within the bowl, said piston being actuated to intermittent displacement partly by pressure of the treated liquid and partly by means of an actuating liquid in-V uenced by centrifugal force, feeding means to conduct the :actuating liquid to an annular groove in the bottom of the bowl and means to conduct the actuating liquid from the said annular groove to a space below said piston, said space being connected with a discharge arrangement for the actuating liquid, this discharge arrangement comprising :a valve means and hydrostatic means for displacement of said valve means to an open position to permit the discharge of the actuating liquid and the simultaneous resulting movement of said piston to its complete open position for sludge discharge, means to permit the actuating liquid constantly to ooze out from the said space, automatic means controlled by the energy contained in the sludge for regulating the ow rate of actuating liquid conducted to the said annular groove, in rela- `tion to Ithe rate of actuating liquid oozing out from the said space, to the effect of displacing said piston to a position for a partial opening of the sludge discharge openings in the bowl and a simultaneous partial sludge discharge, said automatic means holding the piston balanced in its partially open position without stopping the supply to the bowl of the material to be separated, said automatic means comprising a valve member placed in a feed pipe for conducting actuating liquid to said groove and space, the valve member being combined with an elect-ro magnet for control of the valve member, means for regulating the intervals between the partial sludge discharges, the last mentioned means comprising a timer in connection with an electric contacter for intermittent breaking of an electric circuit giving current to the said magnet anda timer and an electric contacter for the closing of the circuit.

5. In the structure of a centrifugal separator as claimed in claim 4 in which the said electric contactor for the closing of the said circuit is actuated by electric tension impulses caused yby the braking eifect from sludge discharges on the driving electric motor.

6. In the structure of a centrifugal separator as claimed in claim 4 in which the said electric means for the closing of the said circuit is actuated by the sludge which is discharged from said peripheral sludge discharge openings, impinging a member connected to a contactor in the circuit of the magnet.

7. In the structure of a centrifugal separator as claimed in claim 4 in which said means to permit the actuating liquid constantly to ooze out of the space beneath the piston is associated with said discharge arrangement for the actuating liquid.

8. yIn the structure of a centrifugal separator as claimed in claim l, in which said means to permit the actuating liquid constantly to ooze out of the space beneath the piston is associated with said discharge arrangement for the actuating liquid.

References Cited in the le of this patent UNITED STATES PATENTS 2,126,864 Bath Aug. 16, 1938 FOREIGN PATENTS 64,790 Denmark Aug. 26, 1946 128,231 Sweden May 9, 1950 312,997 Great Britain Mar. 13, 1930 

